JP2008158398A - Fixing control method and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To attain a satisfactory fixing by minimizing a temperature drop by appropriately utilizing an auxiliary heating and a nip width varying when performing a long paper passing, a wide paper passing or a continuous paper passing in starting a fixing operation immediately just after starting the fixing. <P>SOLUTION: After a power source is turned on, power is supplied to a main heat generating member 13, thereby heating a fixing roller (fixing member) 10. If the temperature of the fixing roller increases beyond a predetermined fixing temperature, paper is immediately inserted to start the fixing operation. In the beginning, the fixing roller is heated by an auxiliary heat generating member 14 together with the main heat generating member 13. Subsequently, the pressing force of a pressure roller (pressing member) 12 on the fixing roller is increased by a nip width varying means 32. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention forms a toner image on an image carrier such as a copying machine, a printer, a facsimile machine or a complex machine thereof, and transfers the toner image to transfer material such as paper, OHP film, cloth, especially roll paper. The present invention relates to an image forming apparatus that records an image on a long or wide transfer material such as a long paper exceeding a standard size. The present invention also relates to a fixing control method for fixing a toner image after image transfer onto a transfer material in such an image forming apparatus.

  Today, as an image forming apparatus such as a copying machine, a printer, and a facsimile, an electrophotographic type is often employed from the viewpoint of high speed, image quality, and economy. In an electrophotographic image forming apparatus, an electrostatic latent image is formed by charging and writing on the photosensitive member as the drum-shaped or belt-shaped photosensitive member rotates, and then a toner is adhered to the developing device. Thus, a visible image is formed to form a toner image, and the toner image is transferred directly or indirectly via an intermediate transfer member, and an image is recorded on the transporting transfer material.

  This type of image forming apparatus includes a fixing device that fixes a toner image after image transfer onto a transfer material. As the fixing device, a heat roll type is most frequently used from the viewpoint of safety and the like. In a heat roll type fixing device, a fixing member such as a fixing roller heated by a heating member such as a halogen heater is pressed against a fixing member such as a pressure roller to form a fixing nip, and a transfer material is formed in the fixing nip. The toner image on the transfer material is fixed to the transfer material by applying heat and pressure.

  However, in recent years, for example, using roll paper, a long transfer material exceeding a standard size or a wide transfer material is used, or images are continuously printed on a transfer material that is relatively long or wide. Image forming apparatuses that can be formed have appeared. In such an image forming apparatus, every time a transfer material is passed through, the fixing device, for example, the heat of the fixing member or the pressure member is greatly deprived by the long transfer material, and the fixing temperature gradually decreases, resulting in poor fixing. There was a risk of causing. In order to solve such a problem, it is preferable to use a fixing member having a large heat capacity. However, when a fixing member having a large heat capacity is used, another problem that the start-up time until the start of paper feeding becomes longer occurs.

  For this reason, in a conventional image forming apparatus, for example, an auxiliary heat generating member is provided in the pressure roller, and when using a long or wide transfer material, the auxiliary heat generating member is used. There is an apparatus that can prevent a decrease in fixing temperature by increasing the amount of heat supplied without increasing the heat capacity of the fixing member. On the other hand, when using a long or wide transfer material, the nip width of the fixing nip is increased in order by increasing the pressure applied by the pressure roller to the fixing roller, so that the amount of heat supplied can be increased stepwise. There is what I did.

JP 2005-221773 A JP 2004-061733 A Japanese Patent Laid-Open No. 03-063167 Japanese Patent Laid-Open No. 2005-235652

  However, when performing long paper feeding or continuous paper feeding, it is not possible to sufficiently suppress the temperature drop of the fixing device by using an auxiliary heating device alone or using a nip width variable means alone. Good fixing could not be performed.

  For example, immediately after the start of fixing, the temperature of the fixing member such as the fixing roller reaches the predetermined fixing temperature, but the pressure member side such as the pressure roller only has the surface temperature reaching the fixing temperature. However, the predetermined fixing temperature has not yet been reached and the heat storage state is not sufficient. When paper feeding is started in this state, there is a drawback that heat is also taken to the pressing member side, and long, wide and continuous paper that can be fixed is restricted.

  Therefore, the first object of the present invention is to perform auxiliary heating and variable nip width when performing a long sheet feeding, a wide sheet feeding, a continuous sheet feeding, etc., when the fixing operation is started immediately after the start of fixing. An object of the present invention is to provide a fixing control method that can be used appropriately and suppress temperature drop to a minimum and perform good fixing.

  On the other hand, since a heat storage effect appears in the pressure member after a while from the start of fixing, the sudden decrease in temperature when paper is passed is gradually alleviated. Therefore, when paper feeding is started after a while from the start of fixing, a paper that is longer, wider, and continuous can be passed than paper that has just passed.

  Therefore, a second object of the present invention is to provide auxiliary heating and a nip width when performing a long paper feed, a wide paper feed, a continuous paper feed, or the like when a paper feed is started after a while from the start of fixing. It is an object of the present invention to provide a fixing control method capable of accurately using variable and minimizing a temperature drop and performing better fixing.

  Also, not only immediately after the start of fixing, but also when the fixing member stops and stands by, because the nip width is fixed, heat transfer occurs only from the fixing nip, so heat storage on the pressure member side Is not done enough. There is a drawback in that long, wide, and continuous paper that can be fixed is restricted.

  Therefore, a third object of the present invention is to perform auxiliary heating and nip when performing long paper feeding, wide paper feeding, continuous paper feeding, etc., when it is determined that the heat storage on the pressure member side is insufficient. It is an object of the present invention to provide a fixing control method capable of performing excellent fixing by appropriately utilizing the variable width and minimizing a temperature drop.

  The fourth object of the present invention is to maintain at least one of the necessary temperature for fixing the toner, the amount of heat necessary for toner fixing, and the amount of heat required for total supply of the transfer material even when the temperature of the fixing member is lowered. It is an object of the present invention to provide a fixing control method capable of performing proper fixing.

  A fifth object of the present invention is to provide a fixing control method capable of charging the auxiliary power source of the auxiliary heating device using the main power source of the main heating device.

  A sixth object of the present invention is to provide a fixing control method that uses a chargeable / dischargeable electric double layer capacitor as an auxiliary power source and can efficiently charge the auxiliary power source.

  The seventh object of the present invention is to efficiently charge the auxiliary power source by the main power source when the auxiliary power is not supplied to the auxiliary heat generating member, while when the auxiliary power is supplied to the auxiliary heat generating member. Another object of the present invention is to provide a fixing control method in which main electric power is also used for a main heat generating member and a higher temperature and heat amount can be supplied to the fixing member.

  An eighth object of the present invention is to provide a fixing control method capable of repeatedly using an auxiliary power source.

  A ninth object of the present invention is to provide a fixing control method capable of grasping the fuel remaining amount of the fuel cell and notifying the user of the necessity of fuel replacement when the fuel remaining amount is below a certain level. It is to provide.

  The tenth object of the present invention is that, when performing long paper feeding, wide paper feeding, continuous paper feeding, etc., the auxiliary heating and the variable nip width are appropriately used to minimize the temperature drop, and good fixing. An object of the present invention is to provide an image forming apparatus capable of performing the above.

For this reason, the invention described in claim 1 is to achieve the first object described above.
A pressure member is pressed against the fixing member to form a fixing nip. The fixing member is passed through the fixing nip through the transfer material and the fixing member is attached to the side where the unfixed toner is not attached. In a fixing control method of an image forming apparatus that fixes a non-fixed toner on a transfer material by contacting a pressure member and applying heat and pressure,
After the power is turned on, when the temperature of the fixing member rises to a predetermined fixing temperature, the fixing operation is started immediately,
First, after heating the fixing member with the auxiliary heating member together with the main heating member,
Next, the pressure applied by the pressure member to the fixing member is increased.

The invention according to claim 2 is to achieve the second object described above.
A pressure member is pressed against the fixing member to form a fixing nip. The fixing member is passed through the fixing nip through the transfer material and the fixing member is attached to the side where the unfixed toner is not attached. In a fixing control method of an image forming apparatus that fixes a non-fixed toner on a transfer material by contacting a pressure member and applying heat and pressure,
After the power is turned on, the fixing member starts a fixing operation after a while after the temperature of the fixing member rises to a predetermined fixing temperature.
First, after increasing the pressing force of the pressure member to the fixing member,
Next, the fixing member is heated by the auxiliary heat generating member together with the main heat generating member.

The invention described in claim 3 is to achieve the third object described above,
A pressure member is pressed against the fixing member to form a fixing nip. The fixing member is passed through the fixing nip through the transfer material and the fixing member is attached to the side where the unfixed toner is not attached. In a fixing control method of an image forming apparatus that fixes a non-fixed toner on a transfer material by contacting a pressure member and applying heat and pressure,
Detecting the temperature of each of the fixing member and the pressure member;
After the power is turned on, when the temperature of the fixing member rises to a predetermined fixing temperature, when the temperature difference between the fixing member and the pressure member is equal to or greater than a certain level, the fixing member is first moved by the auxiliary heating member together with the main heating member. After heating, the pressurizing force of the pressure member against the fixing member is then increased. Conversely, when the temperature difference is less than a certain value, the pressurizing force of the pressurizing member against the fixing member is increased first. Then, the fixing member is heated by the auxiliary heating member together with the main heating member.

  According to a fourth aspect of the present invention, there is provided a fixing control method for an image forming apparatus according to any one of the first to third aspects, wherein the toner fixing required temperature and the toner fixing required heat amount are achieved in order to achieve the fourth object described above. The pressure applied by the pressure member to the fixing member is increased from the time when it falls below the set fixing temperature or the set fixing supply heat amount at which it is determined that it cannot hold any of the heat required for the total fixing supply of the transfer material. It is.

  According to a fifth aspect of the present invention, in order to achieve the fifth object described above, in the fixing control method for an image forming apparatus according to any one of the first to fourth aspects, AC power is supplied from a main power source. The main heat generating member generates heat, and DC power is supplied from an auxiliary power source to generate heat.

  According to a sixth aspect of the present invention, in order to achieve the sixth object described above, in the fixing control method for an image forming apparatus according to the fifth aspect, an electric double layer capacitor is used as the auxiliary power source, and the main heating member. When the AC power is not supplied from the main power source, the auxiliary power source is charged by the main power source.

  According to a seventh aspect of the present invention, in order to achieve the seventh object described above, in the fixing control method for an image forming apparatus according to the sixth aspect, when the auxiliary heat generating member is not heating the fixing member, That is, when the auxiliary heat generating member is not supplied with DC power from the auxiliary power source, the auxiliary power source is charged by the main power source.

  The invention described in claim 8 uses a fuel cell as the auxiliary power supply in the fixing control method for an image forming apparatus according to claim 5 in order to achieve the eighth object described above.

  According to a ninth aspect of the invention, in order to achieve the ninth object described above, in the fixing control method for an image forming apparatus according to the eighth aspect, the remaining amount of fuel in the fuel cell is detected by a remaining amount detecting means. The remaining fuel amount detected by the remaining amount detecting means is notified by the remaining amount notifying means, and when the remaining fuel amount becomes below a certain level, the fuel replacement warning means warns the fuel replacement.

  According to a tenth aspect of the present invention, there is provided a fixing control method for an image forming apparatus according to any one of the first to ninth aspects, in order to achieve the tenth object described above. An image forming apparatus.

  According to the first aspect of the present invention, when the fixing operation is started immediately after the fixing start-up, the nip width is increased after the auxiliary heating is performed, so that the pressure member is still in the pressure accumulation state immediately after the fixing start-up. In consideration of this, when performing long-sheet feeding, wide-width feeding, continuous feeding, etc., the auxiliary heating and variable nip width are appropriately used to minimize the temperature drop and increase the fusing temperature. And good fixing can be performed. Thereby, energy efficiency can be improved and the load to an environment can be reduced.

  According to the second aspect of the present invention, when paper feeding is started after a while from the start of fixing, auxiliary heating is performed after increasing the nip width. Considering the pressure accumulation state, when performing long paper feed, wide paper feed, continuous paper feed, etc., the auxiliary heating and variable nip width are properly used to minimize temperature drop and further fixing Good fixing can be performed by increasing the possible temperature. Thereby, energy efficiency can be improved and the load to an environment can be reduced.

  According to the third aspect of the invention, the temperature of each of the fixing member and the pressure member is detected, the pressure accumulation state of the pressure member is determined based on the temperature difference between the two, and the auxiliary heating and the operation start timing with variable nip width are determined. Therefore, when it is determined that heat storage on the pressure member side is insufficient at the start of paper feeding, when performing long paper feeding, wide paper feeding, continuous paper feeding, etc., auxiliary heating and variable nip width are possible. By properly utilizing the above, it is possible to minimize the temperature drop and to increase the fixable temperature for good fixing. Thereby, energy efficiency can be improved and the load to an environment can be reduced.

  According to the invention described in claim 4, even when the temperature of the fixing member is lowered, at least one of the necessary temperature for fixing the toner, the required amount of heat for fixing the toner, and the required amount of heat for fixing the transfer material is held, Good fixing can always be performed.

  According to the fifth aspect of the present invention, AC power is supplied from the main power source to generate heat from the main heating member, and DC power is supplied from the auxiliary power source to generate heat from the auxiliary heating member. The auxiliary power supply of the auxiliary heating device can be charged using the main power supply.

  According to the sixth aspect of the present invention, since the electric double layer capacitor is used as the auxiliary power source and the AC power is not supplied from the main power source to the main heat generating member, the auxiliary power source is charged by the main power source. An electric double layer capacitor that can be charged and discharged is used as a power source, and the auxiliary power source can be efficiently charged.

  According to the seventh aspect of the present invention, when the auxiliary heat generating member is not heating the fixing member, the auxiliary power source is charged by the main power source, so when the auxiliary power is not supplied to the auxiliary heat generating member, While the auxiliary power source is efficiently charged by the main power source, when the auxiliary power is supplied to the auxiliary heat generating member, the main power is also used for the main heat generating member without charging the auxiliary power source. A higher temperature and heat amount can be supplied to the fixing member.

  According to the eighth aspect of the invention, since the fuel cell is used as the auxiliary power supply, the auxiliary power can be used repeatedly, and auxiliary power can be secured permanently.

  According to the ninth aspect of the present invention, the remaining amount detecting means for detecting the remaining amount of fuel in the fuel cell, the remaining amount notifying means for notifying the remaining amount of fuel detected by the remaining amount detecting means, and the remaining fuel amount Since it is provided with a fuel replacement warning means that warns of fuel replacement when the fuel level becomes below a certain level, the fuel level of the fuel cell can be ascertained by the remaining amount notification means, and when the fuel level falls below a certain level In addition, it is possible to warn the user of the necessity of fuel replacement by the fuel replacement warning means.

  According to the tenth aspect of the present invention, since the image forming apparatus uses the fixing control method for an image forming apparatus according to any one of the first to ninth aspects, When performing paper feeding or continuous paper feeding, the use of auxiliary heating and variable nip width can be appropriately utilized to minimize temperature drop and achieve good fixing.

The best mode for carrying out the present invention will be described below with reference to the drawings.
FIG. 1 shows an overall schematic configuration of an internal mechanism in a wide digital copying machine which is an example of an image forming apparatus.

  In FIG. 1, reference numeral 100 denotes a paper feeding device, 200 denotes an image forming apparatus main body on the paper feeding apparatus 100, and 300 denotes an image reading device (scanner device) on the image forming apparatus main body 200.

  The paper feeder 100 includes roll paper trays 101 and 102 in two upper and lower stages. Each of the roll paper trays 101 and 102 can be pulled out from the sheet feeding device housing in the left direction in the drawing, and is configured so that roll paper can be set and jammed in the pulled-out state. Yes.

  Two roll papers 103 and 104 and two roll papers 105 and 106 wound around the paper tube are set on the roll paper trays 101 and 102, respectively, via a pair of paper holders 107 to 110. It has become. In the vicinity of the roll papers 103 to 106, paper feed rollers 111 to 114 for the roll papers 103 to 106 are arranged, respectively. A roll cutter unit 115 is disposed in a paper feed path 117 downstream of the paper feed rollers 111 and 112 of the roll paper tray 101, and a paper feed path 118 downstream of the paper feed rollers 113 and 114 of the roll paper tray 102. Is provided with a roll cutter unit 116. The paper feed path 118 of the lower roll paper tray 102 continues to the paper feed path 117 of the upper roll paper tray 101.

  Then, the roll paper sent out by each of the paper feed rollers 111 to 114 enters the paper feed paths 117 and 118 on the front side of the tray (left side in the figure) and is fixed to a certain length by the roll cutter units 115 and 116 provided there. The transfer material is cut and sent to the image forming apparatus main body 200 as the transfer material.

  The image forming apparatus main body 200 includes an image forming device 201, a fixing device 202, and a paper discharge device 203 along a paper conveyance path 220. In the image forming device 201, the surface of the photosensitive member 205 that rotates counterclockwise is uniformly charged by the charger 204, and writing is performed by an LED writer (not shown) based on the image signal from the image reading device 300, An electrostatic latent image is formed on the photoreceptor 205. The electrostatic latent image is visualized by attaching toner with a developing device (not shown).

  Along the paper conveyance path 220, a registration roller 208 is upstream of the image forming apparatus 201, and a transfer unit 209 and a separator 210 are positioned downstream of the image forming apparatus 201 and the fixing apparatus 202. A conveyance belt 211 is disposed upstream, and paper discharge rollers 212 and 213 driven by a drive control unit (not shown) are disposed downstream of the fixing device 202. Discharge sensors 215 and 216 are provided in front of both the discharge rollers 212 and 213, respectively. The paper transport path 220 branches downstream of the paper discharge roller 212, and a branching claw 214 is provided at the branch position. A paper discharge tray 206 is provided on the upper surface of the image forming apparatus main body 200, and another paper discharge tray (not shown) is provided behind the image forming apparatus main body 200.

  Then, the transfer material fed from the paper feeding device 100 to the image forming apparatus main body 200 or the transfer material fed from the manual paper feed path 221 is conveyed through the paper conveyance path 220 and is imaged by the registration roller 208. And the toner image formed on the photoconductor 205 is transferred by the transfer unit 209. Thereafter, the toner is separated from the photosensitive member 205 by the separator 210 and guided to the fixing device 202 by the conveying belt 211, and heat and pressure are applied to fix the toner image on the transfer material. The transfer material on which the toner image is fixed is discharged by the discharge roller 212 of the discharge device 203 and discharged onto the discharge tray 206 on the upper surface of the image forming apparatus main body 200 by the discharge roller 213 or by the branching claw 214. The paper discharge direction is switched and the paper is discharged onto a paper discharge tray (not shown) behind the image forming apparatus main body 200 through the branch path. At this time, the paper discharge sensors 215 and 216 determine whether or not the transfer material is in the paper discharge device 203.

  The image reading apparatus 300 includes a document table 301. A document width detection sensor and a document length detection sensor are provided on the document table 301. A document conveyance path 306 is provided in a horizontal direction from the document table 301 to the rear, and along the document conveyance path 306, a paper feed roller 303, a contact image sensor (CIS) 302, a conveyance roller 304, a branching claw 307, A paper roller 305 is disposed. Discharge trays 308 and 309 are attached above and after the image reading apparatus 300, respectively. The image reading apparatus 300 is provided with an operation unit (not shown) for inputting an operation start instruction, a repeat copy, which is information of a transfer material to be conveyed, and long sheet passing information.

  A document is placed on the document table 301 of the image reading apparatus 300, and the size of the document is detected by a document width detection sensor and a document length detection sensor. The documents placed on the document table 301 are aligned in the width direction by a side fence (not shown), fed one by one by a sheet feeding roller 303, and conveyed under the contact image sensor 302. The document under the contact image sensor 302 is exposed by a light source such as an LED array or a fluorescent lamp, and the reflected light is imaged on the image sensor through the rod lens array, and photoelectrically converted to read the content of the document. After the document reading is completed, the paper is discharged onto the paper discharge tray 308 by the conveyance roller 304 and the paper discharge roller 305, or branched by the branching claw 307 and discharged onto the paper discharge tray 309 through the branch path.

  FIG. 2 shows a specific configuration of the fixing device 202 provided in the wide digital copying machine described above.

  A fixing nip N is formed in the fixing device 202 by pressing the pressure roller 12 as a pressure member against the fixing roller 10 as a fixing member. The fixing roller 10 is configured by providing a release layer made of Teflon (registered trademark) or the like around a metal tube such as a cylindrical aluminum tube or carbon steel tube. The pressure roller 12 is provided with a rubber layer made of silicone rubber or the like around a solid cylindrical aluminum tube or carbon steel tube, and a release layer such as a Teflon (registered trademark) tube is provided on the surface of the rubber layer. Provided and configured.

  In the center of the fixing roller 10, a rod-like main heating member 13 such as a halogen heater, a nichrome wire heater, or an IH heater and a rod-like auxiliary heating member 14 such as a halogen heater, a nichrome wire heater, or an IH heater penetrate in parallel. It is inserted. A fixing driving gear 15 is integrally fixed to one end portion of the fixing roller 10. Rotation of an electromagnetic motor 16 using a servo motor or the like is transmitted to the fixing drive gear 15 from the motor gear 17 via a plurality of relay gears 18. When the electromagnetic motor 16 is driven, the pressure roller 12 pressed against the fixing roller 10 is rotated, and the transfer material is conveyed through the fixing nip N.

  On the other hand, first temperature detection means 20 such as a thermistor or a temperature sensor for detecting the surface temperature of the fixing roller 10 is disposed around the fixing roller 10. Further, around the pressure roller 12, a second temperature detecting means 21 such as a thermistor or a temperature sensor for detecting the surface temperature of the pressure roller 12 is disposed.

  FIG. 3 shows the above-described fixing device 202 shown in FIG. 2 together with an electric circuit block for controlling it.

  As shown in the figure, the main heating member 13 provided in the above-described fixing device 202 is connected to a main power supply means 23 having an AC power source 22 as a main power source to constitute a main heating device 24. The main power supply means 23 of the main heating device 24 is connected to the CPU 25. Then, under the control of the CPU 25, AC power is supplied from the AC power supply 22 of the main power supply means 23, and the main heating member 13 is energized to heat the fixing roller 10.

  Further, auxiliary power supply means 27 having an auxiliary power supply 26 is connected to the auxiliary heat generating member 14. The auxiliary power supply 26 includes an electric double layer capacitor that can be charged and discharged, a fuel cell that can be replaced with fuel, and the like. The auxiliary power supply 26 is connected with a voltage sensor 28 as voltage detecting means for detecting the charging voltage. Thereby, an auxiliary heating device 30 including the auxiliary heat generating member 14, the auxiliary power supply means 27, and the voltage sensor 28 is configured. The auxiliary power supply means 27 of the auxiliary heating device 30 is also connected to the CPU 25. The detection result of the voltage sensor 28 is input to the CPU 25. The power is supplied from the auxiliary power supply 26 of the auxiliary power supply means 27 under the control of the CPU 25, and the auxiliary heat generating member 14 is energized to heat the fixing roller 10 together with the main heat generating member 13.

  The first temperature detection means 20 and the second temperature detection means 21 provided in the fixing device 202 described above are also connected to the CPU 25, and the detection results thereof are also input to the CPU 25. On the other hand, a motor driving means 31 is connected to the CPU 25, and the electromagnetic motor 16 is driven by the motor driving means 31 based on a signal from the CPU 25 so that the fixing roller 10 and the pressure roller 12 are rotated. Further, the CPU 25 is connected with a nip width varying means 32, and based on a signal from the CPU 25, the nip width varying means 32 increases or decreases the pressing force of the pressure roller 12 against the fixing roller 10 and the fixing roller 10 and the pressure roller 12. The fixing nip N between them is greatly variable.

FIG. 4 shows a specific configuration of the nip width varying unit 32 of the fixing device 202.
In this example, for example, by driving a variable nip width motor 34 composed of a stepping motor, the wire 52 wound around the rollers 50 and 51 is moved to move the first cam member 53, and the second cam member 54 is rotated to rotate the roller shaft. 44 is moved to control the pressure of the pressure roller 12 against the fixing roller 10 so that the pressure roller 12 can be pressed against the fixing roller 10 with high accuracy in several stages.

FIG. 5 shows another example of the nip width varying means 32 provided in the fixing device 202.
Reference numeral 34 in the drawing is a variable nip width motor as in FIG. The driving force of the variable nip width motor 34 is transmitted from the motor gear 35 via the plurality of gears 36, and the male screw 37 is rotated. The male screw 37 is screwed to the bracket 38, and the rotation direction is reversed by the forward / reverse driving of the variable nip width motor 34, and the bracket 38 is moved in the A or B direction. A reference position of the bracket 38 is detected by the position sensor 40.

  When the bracket 38 is moved, the tension of the spring 41 is increased / decreased, the horizontal cam 42 is rotated, and the vertical cam 43 whose one end is engaged with the horizontal cam 42 is rotated. The other end of the vertical cam 43 is engaged with the roller shaft 44 of the pressure roller 12, and the rotation of the roller shaft 44 moves up and down to increase or decrease the pressure applied between the fixing roller 10 and the pressure roller 12. The That is, the driving force of the variable nip width motor 34 as a driving means is transmitted by a driving transmission means comprising a plurality of gears 36, male screws 37, brackets 38, springs 41, horizontal cams 42, etc., and a vertical cam 43 as a cam member. And the elastic deformation of the rubber layer of the pressure roller 12 is changed to change the nip width of the fixing nip N. As a result, the time for the transfer material 45 to pass through the fixing nip N changes, and the amount of heat supplied to the transfer material 45 is controlled.

FIG. 6 shows an example of a control flow by the nip width varying means 32 as shown in FIGS. In this example, the nip width is controlled in five stages.
When the nip width of the fixing nip N between the fixing roller 10 and the pressure roller 12 is controlled, first, the pressure amount of the pressure roller 12 with respect to the fixing roller 10 is set to the minimum and the nip amount is in the first stage at the minimum. (step S1), and detects the temperature _{T H} of the fixing roller 10 by the first temperature detecting means 20 (step S2).

If the temperature _TH is 180 ° C. or higher, there is no need to change the nip width, but if it is 180 ° C. or lower (step S3), if it is 170 ° C. or higher and lower than 180 ° C. (step S4), the fixing roller 10 The pressure amount of the pressure roller 12 is increased and the nip amount is set to the second stage (step S5). If the temperature is 160 ° C. or higher and lower than 170 ° C. (step S6), the pressure amount of the pressure roller 12 is further increased to set the nip amount to the third stage (step S7). If the temperature is 150 ° C. or higher and lower than 160 ° C. (step S8), the pressure amount of the pressure roller 12 is further increased to set the nip amount to the fourth stage (step S9).

  If the temperature is less than 150 ° C., the amount of pressure applied by the pressure roller 12 to the fixing roller 10 is increased to the maximum, and the nip amount is set to the fifth stage (step S10). Next, it is determined whether or not the control is to be continued (step S11). If the control is continued, the process returns to step S2 and is repeated in the same manner.

  FIG. 7 shows an example of a fixing control method in the fixing device 202 of the wide digital copying machine described above.

  For example, when an image is formed on a long transfer material having a length of 15 m or a wide transfer material of A2 or larger, or when an image is continuously formed on a transfer material having a size of A2, a large transfer material is passed. As a result, in the fixing device 202, the heat of the fixing roller 10 and the pressure roller 12 may be gradually taken away by the transfer material and the fixing temperature may be lowered, resulting in a fixing failure. FIG. And a fixing control method when an image is formed on a wide transfer material or when a continuous sheet is passed.

  As shown in the figure, when the power of the copying machine is turned on, it is controlled by the CPU 25. First, in step S1, the main heating device 24 is driven to supply power from the AC power supply 22 of the main power supply means 23, and the main heating member. 13 is energized, and the fixing roller 10 is heated by the main heating member 13.

FIG. 8 shows the relationship between the time from when the copier is turned on and the surface temperatures of the fixing roller 10 and the pressure roller 12.
As shown in FIG. 8, the surface temperature of the fixing roller 10 increases rapidly with the heating by the main heat generating member 13, and the detected temperature by the first temperature detecting means 20 is about 195 ° C., which is the predetermined fixing temperature in about 80 seconds. become. At this time, the temperature detected by the second temperature detecting means 21 of the pressure roller 12 is about 80 ° C., and the pressure is not completely accumulated. If it is completely stored, the rate of change of temperature will be lower.

  When the first temperature detection unit 20 detects that the surface temperature of the fixing roller 10 has risen to 195 ° C., which is a predetermined fixing temperature, in step S2 of FIG. 7, the paper feeding starts in the next step S3. Then, the toner image is transferred to the transfer material 45, and the transfer material 45 on which the toner image is transferred is inserted into the fixing nip N of the fixing device 202.

FIG. 9 shows a fixing state by the fixing device 202.
When the paper is passed, the transfer roller 45 inserted into the fixing nip N has the fixing roller 10 on the side where the unfixed toner is attached and the pressure roller 12 on the side where the unfixed toner is not attached. Heat and pressure are applied in contact. Then, the toner image 47 thereon is fixed on the transfer material 45 as it passes through the fixing nip N.

  When the paper is passed, heat is taken away by the large transfer material 45 and the surface temperatures of the fixing roller 10 and the pressure roller 12 are lowered. Therefore, in the next step S4, the auxiliary heating device 30 is driven, electric power is supplied from the auxiliary power supply 26 of the auxiliary power supply means 27, and the auxiliary heat generating member 14 is energized. Then, in addition to the heating of the main heating member 13, heating by the auxiliary heating member 14 is started. Therefore, as shown in FIG. 8, the surface temperature of the fixing roller 10 is maintained at a substantially high temperature, although it slightly decreases.

  However, if an electric double layer capacitor is used for the auxiliary power supply 26, for example, the voltage gradually decreases due to the discharge due to the characteristics of the electric double layer capacitor, and the required minimum amount of supplied heat cannot be maintained. Although it depends on the performance of the capacitor, the time is usually around 100 s. Accordingly, in the next step S5, it is determined whether or not a fixed time of about 100 s has elapsed since the start of fixing. If it is determined that the time has elapsed, in step S6, the power supply to the auxiliary power source 26 is stopped, and the auxiliary heat generating member. The energization to 14 is stopped. Then, as shown in FIG. 8, the surface temperature of the fixing roller 10 gradually decreases.

  In the next step S7, when it is determined that the surface temperature of the fixing roller 10 is equal to or lower than the set fixing temperature set appropriately, and the supplied heat amount is insufficient, the nip width varying means 32 is driven and fixed in step S8. The pressing force of the pressure roller 12 against the roller 10 is increased, and the initially set minimum nip width (L in FIG. 9) is increased by one step. Next, in step S9, it is determined whether or not the nip width is a maximum that can be set. If not, the process returns to step S7, and then the surface temperature of the fixing roller 10 is again supplied below the set fixing temperature. The sheet passing is continued until it is determined that the amount of heat is insufficient, and when the temperature becomes equal to or lower than the set fixing temperature, the nip width is further increased in step S8. Then, in step S9, this is repeated until it is determined that the nip width is the maximum that can be set, and control is performed to increase the nip width L stepwise to increase the supply heat amount step by step. As a result, as shown in FIG. 8, the temperature of the fixing roller 10 is maintained at a fixing temperature of 135 ° C. or higher for about 220 s.

  When it is determined in step S9 that the nip width is the maximum that can be set, in step S10, the sheet is passed until it is finally determined that the surface temperature of the fixing roller 10 is equal to or lower than the set fixing temperature and the supply heat amount is insufficient. Continue. When the surface temperature of the fixing roller 10 is equal to or lower than the set fixing temperature, the process proceeds to step S11, where the nip width variable means 32 is driven to return the nip width to the initial minimum, and in subsequent step S12, the paper feeding is interrupted. Then, the process returns to step S2, and it is determined whether or not the surface temperature of the fixing roller 10 has increased to a predetermined fixing temperature. Then, the paper feeding is started again and continued until the job is finished.

FIG. 10 shows an electric circuit for operating the fixing device 202 described above.
In the drawings, similarly, 10 is a fixing roller, 12 is a pressure roller, 13 is a main heat generating member, 14 is an auxiliary heat generating member, 20 is first temperature detecting means, 21 is second temperature detecting means, and 22 is A main power source, 25 is a CPU, 26 is an electric double layer capacitor, and 27 is an auxiliary power supply means.

  Next, in FIGS. 11A to 11E, in the case where long paper exceeding a standard size is used for the auxiliary power supply 26 of the fixing device 202 described above using an electric double layer capacitor, the fixing is performed after the power is turned on. When starting the fixing operation immediately when the temperature of the member rises to the predetermined fixing temperature, the transition of the fixing roller temperature, the transition of the total power consumption of the fixing heater, the transition of the AC power consumption of the fixing heater, the assist of the fixing heater consumption Power transition and capacitor charging on / off timing are shown respectively.

The t1 section is a section that rises up to a predetermined fixing temperature _Tt . When the auxiliary heat generating member 14 is heated by supplying electric power from the electric double layer capacitor as the auxiliary power source 26 in the t1 section, the predetermined fixing temperature is reached. Time to reach the temperature can be reduced.

Next, a period t2 is a waiting state in which a copy original is read, a printer job is waited, or both are not performed, and the AC power supply 22 is turned on / off in order to maintain a predetermined fixing temperature T _t . Therefore, if there remains room for charging the electric double layer capacitor by the voltage sensor 28 that detects the charging voltage of the electric double layer capacitor, which is the auxiliary power supply 26, the AC power source 22 is used to supply power to the main heating member 13. When not, the AC power of the AC power source 22 is used to charge the electric double layer capacitor. When it is detected by the voltage sensor 28 that the electric double layer capacitor is sufficiently charged, the electric double layer capacitor is not charged until the voltage sensor 28 detects a room for charging.

  In section t3, after the end of reading of the long document by the image reading apparatus 300 or the end of reading of the printer job of the long sheet passing information, the long sheet passing exceeding the standard size is started, and the main heat generation from the AC power source 22 is started. This is a section in which power is supplied to the auxiliary heat generating member 14 from the electric double layer capacitor as the auxiliary power supply 26 while AC power is supplied to the member 13. Therefore, in the fixing heater total power consumption transition (B), the power consumption transitions by the sum of the consumption AC power transition (C) and the consumption auxiliary power (D). In the case of FIG. 11, the total power consumption of the fixing heater decreases with time. This is because the output decreases as the electric double layer capacitor continues to discharge. The power reduction discharge curve is determined by the capacitance of the capacitor, the output setting, and the like.

  Here, the toner fixing necessary temperature and the toner fixing necessary heat amount are characteristic values of the toner to be used, and the transfer material necessary heat amount is a characteristic value of the transfer material to be used. In FIG. 9, heat is transferred between the fixing nip N portion where the fixing roller 10 and the pressure roller 12 are in pressure contact, the toner image 47, and the transfer material 45.

The amount of fixing heat Q _{H applied} to the toner image 47 and the transfer material 45 on the fixing roller 10 side is calculated by the equation (1) in Table 1. Heat supplied Q _P applied to the pressure roller 12 side of the transfer material 45 is calculated by the Table 1 of formula (2). Also, the total fixing supply heat amount Q _T given to the front and back surfaces of the toner image 47 and the transfer material 45 is calculated by the equation (3) in Table 1. The temperature of the fixing roller 10 does not fall below the required toner fixing temperature, Q _H does not fall below the required amount of heat required for toner fixing, which is a toner characteristic value, and Q _T does not fall below the required total heat supply required for fixing. Is monitored while calculating in the control, and it is determined that the toner fixing required temperature, the toner fixing required heat amount, and the total fixing supply heat amount of the transfer material 45 cannot be held only by the AC power. The reason that the AC power at the time of passing the paper at t3 is smaller than that at the start of t1 is that a part of the AC power is converted into DC power and used for the operation of other mechanisms during the copying operation.

The t4 section is a section in which the long sheet passing ends and AC power is supplied from the AC power source 22 to the main heat generating member 13 so that the temperature of the fixing roller 10 is returned to the predetermined fixing temperature _Tt again. If the auxiliary power is supplied to the auxiliary heat generating member 14 in this section, the time until the predetermined fixing temperature is reached can be reduced.

A period t5 is a waiting state in which a copy original is read, a printer job is waited for, or both are not performed, and the AC power supply 22 is turned on and off in order to maintain a predetermined fixing temperature T _t . Therefore, when there is still room for charging the electric double layer capacitor by the voltage sensor 28 that detects the charging voltage of the electric double layer capacitor, the AC power is electric when the AC power source 22 is not used for the main heating member 13. Used to charge double layer capacitors. When the voltage sensor 28 detects that the electric double layer capacitor is sufficiently charged, the electric double layer capacitor is not charged until the voltage sensor 28 detects a room for charging.

  When the auxiliary heat generating member 14 is not heating the fixing roller 10, that is, when DC power is not supplied to the auxiliary heat generating member 14 from the auxiliary power supply 26, the auxiliary power supply 26 is charged by the main power supply 22. In this way, when the auxiliary power is not supplied to the auxiliary heat generating member 14, the auxiliary power supply 26 is efficiently charged by the main power supply 22, while when the auxiliary power is supplied to the auxiliary heat generating member 14, Without charging the power supply 26, main power is also used for the main heat generating member 13, and the main heat generating member 13 and the auxiliary heat generating member 14 can supply a higher temperature and heat amount to the fixing roller 10.

In the fixing control method shown in FIGS. 11A to 11E, after the power is turned on, when the surface temperature of the fixing roller 10 reaches the predetermined fixing temperature _Tt , the fixing operation is started immediately, and the auxiliary heat generating member is used. 14 was heated for a certain period of time to prevent a temperature drop. Thereafter, the pressure member for the fixing member from the time when it falls below the set fixing temperature and the set fixing supply heat amount at which it is judged that any one of the necessary temperature for toner fixing, the required heat amount for toner fixing, and the required total heat supply amount for the transfer material cannot be maintained. The nip width is increased stepwise by increasing the pressure applied to increase the amount of heat supplied to the toner of the transfer material 45.

  This is because when the surface temperature of the fixing roller 10 reaches the predetermined fixing temperature, the temperature on the pressure roller 12 side has not yet risen completely, and the heat storage state is not complete. When the control is performed, when the nip width is widened, the heat on the fixing roller 10 side escapes to the pressure roller 12 side via the transfer material 45, and the amount of heat cannot be efficiently applied to the transfer material 45. Because.

  Then, the pressure roller 12 together with the transfer material 45 is deprived of heat and the surface temperature of the fixing roller 10 rapidly decreases as shown in FIG. In this case, the fixing possible temperature of 135 ° C. is interrupted, and the fixing possible time is about 150 seconds, so that the temperature maintenance time becomes extremely shorter than the above example. Therefore, when the pressure roller 12 is not in the heat storage state, the fixing control method in which auxiliary heating is first performed and then the nip width is increased, as in the above-described fixing control method.

  Next, in FIGS. 13A to 13E, in the case where long paper passing over a standard size is performed using the electric double layer capacitor for the auxiliary power source 26 of the fixing device 202 described above, the fixing is performed after the power is turned on. When a fixing operation is started after a while after the temperature of the member rises to a predetermined fixing temperature, the fixing roller temperature transition, the fixing heater total power consumption transition, the fixing heater consumption AC power transition, the fixing, The heater consumption auxiliary power transition and the capacitor charge on / off timing are respectively shown.

The t1 section is a section that rises up to a predetermined fixing temperature _{Tt. When} power is supplied from the electric double layer capacitor as the auxiliary power source 26 in the t1 section and the auxiliary heat generating member 14 generates heat, the predetermined fixing is performed. Time to reach the temperature can be reduced.

Next, a period t2 is a waiting state in which a copy original is read, a printer job is waited, or both are not performed, and the AC power supply 22 is turned on / off in order to maintain a predetermined fixing temperature T _t . Therefore, if there remains room for charging the electric double layer capacitor by the voltage sensor 28 that detects the charging voltage of the electric double layer capacitor, which is the auxiliary power supply 26, the AC power source 22 is used to supply power to the main heating member 13. When not, the AC power of the AC power source 22 is used to charge the electric double layer capacitor. When it is detected by the voltage sensor 28 that the electric double layer capacitor is sufficiently charged, the electric double layer capacitor is not charged until the voltage sensor 28 detects a room for charging.

  In section t3, after the end of reading of the long document by the image reading apparatus 300 or the end of reading of the printer job of the long sheet passing information, the long sheet passing exceeding the standard size is started, and the main heat generation from the AC power source 22 is started. This is a section in which AC power is supplied to the member 13 and paper is passed. Therefore, the fixing heater total power consumption transition (B) is equivalent to the consumption AC power transition (C).

  Here, the toner fixing necessary temperature and the toner fixing necessary heat amount are characteristic values of the toner to be used, and the transfer material necessary heat amount is a characteristic value of the transfer material to be used. In FIG. 9, heat is transferred between the fixing nip N portion where the fixing roller 10 and the pressure roller 12 are in pressure contact, the toner image 47, and the transfer material 45.

The amount of fixing heat Q _{H applied} to the toner image 47 and the transfer material 45 on the fixing roller 10 side is calculated by the equation (1) in Table 1. Heat supplied Q _P applied to the pressure roller 12 side of the transfer material 45 is calculated by the Table 1 of formula (2). Also, the total fixing supply heat amount Q _T given to the front and back surfaces of the toner image 47 and the transfer material 45 is calculated by the equation (3) in Table 1. The temperature of the fixing roller 10 does not fall below the required toner fixing temperature, Q _H does not fall below the required amount of heat required for toner fixing, which is a toner characteristic value, and Q _T does not fall below the required total heat supply required for fixing. Is monitored while calculating in the control, and it is determined that the toner fixing required temperature, the toner fixing required heat amount, and the total fixing supply heat amount of the transfer material 45 cannot be held only by the AC power. The reason that the AC power at the time of passing the paper at t3 is smaller than that at the start of t1 is that a part of the AC power is converted into DC power and used for the operation of other mechanisms during the copying operation.

  In the t4 section, the paper was passed while supplying heat by the main heat generating member 13 in the t3 section. However, the fixing temperature limit was detected by the first temperature detecting means 20, and the electric double layer capacitor as the auxiliary power source 26 was installed. This is a section where continuous paper is continuously fed while supplying auxiliary heat to the auxiliary heat generating member 14. Therefore, in the fixing heater total power consumption transition (B), the power consumption is the sum of the AC power consumption (C) and the auxiliary power consumption (D). In the case of FIG. 12, the total power consumption of the fixing heater decreases with time. This is because the output decreases as the electric double layer capacitor continues to discharge. The power reduction discharge curve is determined by the capacitance of the capacitor, the output setting, and the like.

The t5 section is a section in which the long sheet passing is completed and AC power is supplied from the AC power source 22 to the main heat generating member 13 to return the temperature of the fixing roller 10 to the predetermined fixing temperature _Tt again. If the auxiliary power is supplied to the auxiliary heat generating member 14 in this section, the time until the predetermined fixing temperature is reached can be reduced.

A period t6 is a waiting state in which a copy original is read, a printer job is read, or both are not performed, and the AC power source 22 is turned on / off to maintain a predetermined fixing temperature T _t . Therefore, when there is still room for charging the electric double layer capacitor by the voltage sensor 28 that detects the charging voltage of the electric double layer capacitor, the AC power is electric when the AC power source 22 is not used for the main heating member 13. Used to charge double layer capacitors. When the voltage sensor 28 detects that the electric double layer capacitor is sufficiently charged, the electric double layer capacitor is not charged until the voltage sensor 28 detects a room for charging.

By the way, in the fixing control method shown in FIGS. 13A to 13E, after the power is turned on, the fixing operation is started after a while after the surface temperature of the fixing roller 10 rises to the predetermined fixing temperature _Tt. The fixing roller 110 is heated by the auxiliary heat generating member 14 together with the main heat generating member 13. As described above, when a certain amount of time elapses after the start of fixing, a heat storage effect appears in the pressure roller 12, so that a sudden temperature drop is gradually mitigated when the paper is passed. Therefore, when paper feeding is started after some time has passed since the start of fixing, continuous, wide, and continuous paper feeding is possible as compared to paper feeding immediately after the rising.

  Therefore, in this case, from the time when the temperature is lower than the set fixing temperature and the set fixing supply heat amount at which it is judged that any one of the necessary temperature for toner fixing, the necessary heat amount for toner fixing, and the required total heat supply amount for the transfer material cannot be maintained, A temperature drop is prevented by increasing the pressure force of the pressure member to the fixing member and increasing the nip stepwise. Thereafter, the auxiliary heating member 14 is turned on to perform auxiliary heating. Thus, when the pressure roller 12 is in a heat storage state, this is more efficient and advantageous.

  14A to 14E, in the case where long paper exceeding a standard size is used for the auxiliary power supply 26 of the fixing device 202 described above using a fuel cell, the temperature of the fixing member is predetermined after the power is turned on. When the fixing operation is started after a while after the fixing temperature rises, the fixing roller temperature transition, the fixing heater total power consumption transition, the fixing heater consumption AC power transition, the fixing heater consumption auxiliary power transition until the nip width variable start The capacitor charging on-off timing is shown respectively.

The t1 section is a section in which the temperature is raised to a predetermined fixing temperature _Tt , and shows a fixing temperature transition due to heat generation of the main heat generating member 13 using only the AC power source 22. Here, if power is also supplied from the fuel cell as the auxiliary power source 26 during the t1 period to cause the auxiliary heat generating member 14 to generate heat, the time required to reach the predetermined fixing temperature can be reduced.

Next, a period t2 is a waiting state in which a copy original is read, a printer job is waited, or both are not performed, and the AC power supply 22 is turned on / off in order to maintain a predetermined fixing temperature T _t .

  In the period t3, after the end of the reading of the long document by the image reading apparatus 300 or the end of the reading of the printer job of the long paper passing information, the long paper passing exceeding the standard size is started, and the AC power from the AC power source 22 is started. Electric power is supplied to the main heating member 13 to thermally fix the toner on the transfer material 45, and from the surface temperature of the fixing roller 10 and the pressure roller 12 detected by the temperature detecting means 20, 21, the toner fixing required temperature or toner fixing is performed. This is the interval up to the point where it is determined that the necessary heat amount and the total heat supply amount required for fixing the transfer material 45 cannot be maintained only by the AC power.

  Here, the toner fixing necessary temperature and the toner fixing necessary heat amount are characteristic values of the toner to be used, and the transfer material necessary heat amount is a characteristic value of the transfer material to be used. In FIG. 9, heat is transferred between the fixing nip N portion where the fixing roller 10 and the pressure roller 12 are in pressure contact, the toner image 47, and the transfer material 45.

The amount of fixing heat Q _H given to the toner image 47 is calculated by the equation (1) in Table 1. The fixing total supplied heat quantity Q _T to be applied to the transfer material 45 is calculated by the Table 1 of formula (2). The temperature of the fixing roller 10 does not fall below the required toner fixing temperature, Q _H does not fall below the required amount of heat required for toner fixing, which is a toner characteristic value, and Q _T does not fall below the required total heat supply required for fixing. Is monitored while calculating in the control, and it is determined that the toner fixing required temperature, the toner fixing required heat amount, and the total fixing supply heat amount of the transfer material 45 cannot be held only by the AC power. The reason that the AC power at the time of passing the paper at t3 is smaller than that at the start of t1 is that a part of the AC power is converted into DC power and used for the operation of other mechanisms during the copying operation.

  The t4 section is a section in which power is supplied from the fuel cell as the auxiliary power supply 26 to the auxiliary heat generating member 14 while supplying AC power from the AC power source 22 to the main heat generating member 13. Therefore, in the fixing heater total power consumption transition (B), the total power consumption of the fixing heater is discontinuous from the moment when the total power consumption of the fixing heater shifts from the t3 section to the t4 section by adding the AC power consumption (C) and the auxiliary power consumption (D). The fixing temperature of the fixing roller 10, the amount of heat for fixing, and the total amount of heat supplied by fixing are maintained or increased.

  By the way, in the fuel cell, the fuel gradually decreases by discharging. Therefore, when a fuel cell is used for the auxiliary power source 26, the remaining amount detecting means for detecting the remaining amount of fuel in the fuel cell and constantly monitoring the remaining amount of fuel that is reduced by use, and the fuel detected by the remaining amount detecting means Remaining amount notifying means for notifying the user of the remaining amount appropriately using a display unit and the like, and a fuel replacement warning means for displaying a warning, for example, to warn the user when the remaining fuel amount is below a certain level With. When the user recognizes that the remaining fuel amount is low by the fuel replacement warning means, for example, the cartridge type battery fuel is replaced with a new one.

The t5 section is a section in which the long sheet passing is completed and AC power is supplied from the AC power source 22 to the main heat generating member 13 to return the temperature of the fixing roller 10 to the predetermined fixing temperature _Tt again. If the auxiliary power is supplied to the auxiliary heat generating member 14 in this section, the time until the predetermined fixing temperature is reached can be reduced.

A period t6 is a waiting state in which a copy original is read, a printer job is read, or both are not performed, and the AC power source 22 is turned on / off to maintain a predetermined fixing temperature T _t .

  Now, not only when the power is turned on, but also in a standby state, the fixing roller 10 and the pressure roller 12 are stopped and the fixing nip N does not move, so heat transfer occurs only from the fixing nip N. In addition, heat storage on the pressure roller 12 side is not sufficiently performed over the entire circumference. Therefore, if the temperature of both the fixing roller 10 and the pressure roller 12 is detected using the first temperature detection means 20 and the second temperature detection means 21 and the temperature difference is equal to or greater than a predetermined value, the pressure roller 12 It is determined that the heat storage state is not sufficient, and first, heating control by an auxiliary heating device is performed, and second, nip control by nip width varying means is performed. On the contrary, if the temperature difference is less than the predetermined value, it is determined that the pressure roller 12 is in a sufficient heat storage state, and the nip control is performed first, and the heating control is performed second.

  In the use of the auxiliary power source 26 shown in FIGS. 11, 13, and 14, in all cases, the nip width varying means is controlled as shown in FIG. By controlling the combined nip amount to suppress excessive supply of heat, the gradient of temperature drop is suppressed compared to when the nip amount is constant, and heat consumption during long sheet passing, that is, power consumption, is reduced. The paper can be passed to save energy. Here, the nip amount corresponding to each temperature band is determined experimentally or according to the target heat amount by the calculation formula shown in Table 1.

  In the configuration in which the nip amount is constant, it is necessary to configure the nip amount large so that the fixing supply heat amount supplied to the toner image 47 and the transfer material 45 is sufficient at the fixing limit temperature, and the fixing roller temperature is fixed. When the temperature is above the limit temperature, the fixing supply heat amount is always excessive. Therefore, when the nip amount is constant, a larger amount of heat is consumed and the temperature decrease gradient becomes larger than when pressurization control and nip amount control for keeping the fixing supply heat amount constant. In addition, when pressurization control and nip amount control are performed compared to when the nip amount is constant, the fixing ability of long-distance paper passing over a longer distance than when the nip amount is constant can be achieved with a certain amount of heat supply. It can be guaranteed.

1 is an overall schematic configuration diagram of an internal mechanism in a wide digital copying machine which is an example of an image forming apparatus. FIG. 3 is a specific configuration diagram of a fixing device provided in the wide digital copying machine. It is a figure which shows the fixing device shown in FIG. 2 with the electric circuit block which controls it. It is a specific block diagram of a nip width varying means of the fixing device. FIG. 6 is a specific configuration diagram of another example of a nip width varying unit provided in the fixing device. It is a control flow figure of a nip width variable means. 3 is a flowchart showing an example of a fixing control method in the fixing device of the wide digital copying machine shown in FIG. 1. FIG. 5 is a relationship diagram between the time from when the copier is turned on and the surface temperatures of the fixing roller and the pressure roller. FIG. 3 is a diagram showing a fixing state by the fixing device shown in FIG. 2. FIG. 3 is an electric circuit diagram for operating the fixing device shown in FIG. 2. When long paper is passed using an electric double layer capacitor as an auxiliary power source for the fixing device, the nip width can be changed when the fixing member reaches the predetermined fixing temperature and starts fixing immediately after the power is turned on. 6 is a timing chart of heating control of the fixing roller until the start. FIG. 6 is another diagram showing the relationship between the time from when the copier is turned on and the surface temperatures of the fixing roller and the pressure roller. When using the electric double layer capacitor as an auxiliary power source for the fixing device and starting the fixing operation after a while after the temperature of the fixing member rises to the predetermined fixing temperature after turning on the power. 6 is a timing chart of heating control of the fixing roller until the nip width variable start. When using a fuel cell as the auxiliary power source of the fixing device and passing a long sheet of paper, after the power is turned on, when the fixing operation starts for a while after the temperature of the fixing member rises to the predetermined fixing temperature, the nip 6 is a timing chart of heating control of the fixing roller until the start of variable width.

Explanation of symbols

10 Fixing roller (fixing member)
12 Pressure roller (pressure member)
13 Main heating member 14 Auxiliary heating member 20 First temperature detection means 21 Second temperature detection means 22 AC power supply (main power supply)
24 Main heating device 26 Auxiliary power supply 28 Voltage sensor (voltage detection means)
30 Auxiliary heating device 32 Nip width variable means 34 Nip width variable motor 45 Transfer material 47 Toner image 202 Fixing device L Nip width N Fixing nip T _t Predetermined fixing temperature

Claims (10)

A pressure member is pressed against the fixing member to form a fixing nip. The fixing member is passed through the fixing nip through the transfer material and the fixing member is attached to the side where the unfixed toner is not attached. In a fixing control method of an image forming apparatus that fixes a non-fixed toner on a transfer material by contacting a pressure member and applying heat and pressure,
After the power is turned on, when the temperature of the fixing member rises to a predetermined fixing temperature, the fixing operation is started immediately,
First, after heating the fixing member with the auxiliary heating member together with the main heating member,
Next, the pressing force of the pressure member against the fixing member is increased.
A fixing control method for an image forming apparatus. A pressure member is pressed against the fixing member to form a fixing nip. The fixing member is passed through the fixing nip through the transfer material and the fixing member is attached to the side where the unfixed toner is not attached. In a fixing control method of an image forming apparatus that fixes a non-fixed toner on a transfer material by contacting a pressure member and applying heat and pressure,
After the power is turned on, the fixing member starts a fixing operation after a while after the temperature of the fixing member rises to a predetermined fixing temperature.
First, after increasing the pressing force of the pressure member to the fixing member,
Next, the fixing member is heated with an auxiliary heating member together with the main heating member.
A fixing control method for an image forming apparatus. A pressure member is pressed against the fixing member to form a fixing nip. The fixing member is passed through the fixing nip through the transfer material and the fixing member is attached to the side where the unfixed toner is not attached. In a fixing control method of an image forming apparatus that fixes a non-fixed toner on a transfer material by contacting a pressure member and applying heat and pressure,
Detecting the temperature of each of the fixing member and the pressure member;
After the power is turned on, when the temperature of the fixing member rises to a predetermined fixing temperature, when the temperature difference between the fixing member and the pressure member is equal to or greater than a certain level, the fixing member is first moved by the auxiliary heating member together with the main heating member. After heating, the pressurizing force of the pressure member against the fixing member is then increased. Conversely, when the temperature difference is less than a certain value, the pressurizing force of the pressurizing member against the fixing member is increased first. Then, the fixing member is heated by the auxiliary heating member together with the main heating member.
A fixing control method for an image forming apparatus.   The pressure member for the fixing member from the time when the temperature is lower than the set fixing temperature and the set fixing supply heat amount at which it is judged that any one of the necessary temperature for toner fixing, the required heat amount for toner fixing, and the required total heat supply amount for the transfer material cannot be maintained 4. The fixing control method for an image forming apparatus according to claim 1, wherein the pressure is increased.   The AC power is supplied from a main power source to generate heat from the main heating member, and the DC power is supplied from an auxiliary power source to generate heat from the auxiliary heating member. And a fixing control method for the image forming apparatus.   6. An electric double layer capacitor is used as the auxiliary power source, and the auxiliary power source is charged by the main power source when AC power is not supplied from the main power source to the main heat generating member. And a fixing control method for the image forming apparatus.   7. The fixing control method for an image forming apparatus according to claim 6, wherein the auxiliary power source is charged by the main power source when the auxiliary heat generating member is not heating the fixing member.   6. The fixing control method for an image forming apparatus according to claim 5, wherein a fuel cell is used as the auxiliary power source.   The remaining amount of fuel in the fuel cell is detected by the remaining amount detecting means, the remaining amount of fuel detected by the remaining amount detecting means is notified by the remaining amount notifying means, and the fuel is replaced when the remaining fuel amount becomes below a certain level. 9. The fixing control method for an image forming apparatus according to claim 8, wherein a warning is given by a fuel replacement warning means.   An image forming apparatus using the fixing control method for an image forming apparatus according to claim 1.

Images